Sulfonated condensation products which are stabile in storage, method for the production thereof, and their use

ABSTRACT

Sulfonated condensation products that are stable in storage and have increased thermal stability are based on aminoplastic formers having at least two amino groups or naphthalene and formaldehyde and, optionally include organic nitrogen bases which additionally contain, as nitrogenous formulation auxiliary agents, compounds of general formula (I) R 1 —NH—X—Y—R 2 , wherein R 1  and R 2  independently represent H, —CH 3 , —C 2 H 5 , —C 3 H 7 , —(CH 2 ) n —CH 2 —; X═—CH 2 , CO, CS; Y═S, NH, —(CH 2 ) m —; n=0 to 9; m=1 to 4; and/or compounds of general formula (II), 
                 
         wherein Z═—OCH 3 , —SO 3 —H, —SO 3 Na + , —NO 2 , —NH 2 , —NH—NH 2 , —CO 2 —Na + , —CHO. The mole ratio of aminoplastic formers: formaldehyde: sulfite: nitrogenous formulation auxiliary agents rangin from 1:1.9 to 6.0:1.0 to 2.0:0.01 to 1.5 and/or the mole ratio of naphthalene sulfonic acid: formaldehyde; nitrogenous formulation auxiliary agents equals 1:0.7 to 3.0:0.01 to 1.5. Method for preparing these condensation products of using them, e.g., as additives for inorganic binding agents and for hydraulically setting dry mixtures that contain inorganic binding agents are also disclosed.

The present invention relates to storage-stable sulfonated condensationproducts, a process for preparing them and their use.

It is sufficiently known that hydraulically setting binders such ascement, lime, gypsum, CaSO₄ hemihydrates and anhydrites can be fluidizedby addition of dispersants, which makes it possible to set desired lowwater/binder ratios. Classical dispersants which have been used for over20 years are melamine-formaldehyde-sulfite (MSF) resins andnaphthalenesulfonic acid-formaldehyde (NSF) resins which have beencontinuously developed further in recent years so as to be able to meetincreased expectations.

Thus, DE 195 38 821 describes low-cost MFS resins containing a highproportion of sulfite. According to EP 690 083, a cost reduction isachieved by partial replacement of melamine by urea in a 2-stage processwith addition of coreactants such as aminosulfonic acids,aminocarboxylic acids and caprolactam, etc., although this advantage ispartly negated by an oxidation step to eliminate the excess sulfite.

Also customary is the addition of sulfanilic acid, as disclosed, forexample, in DE 44 11 797 or in DE 196 09 614, in which case thesulfanilic acid is supplemented by polyoxyalkylene derivatives and/oraldehyde acid derivatives.

However, all these condensation products have the disadvantage that thespray drying of aqueous solutions of conventional fluidizers has anextremely adverse effect on the early strength development which is ofparticular importance for CaSO₄ applications due to the high thermalstress during drying.

It is therefore an object of the present invention to developstorage-stable sulfonated condensation products based on an amino resinformer having at least two amino groups and sulfite and/ornaphthalenesulfonic acid together with formaldehyde which when used asadditives for hydraulically setting additives do not display theabovementioned disadvantage of a thermal change but are instead stableover a wide temperature range.

According to the invention, this object is achieved by sulfonatedcondensation products which further comprise at least onenitrogen-containing formulation auxiliary selected from among compoundsof the formula (I)R¹—NH—X—Y—R²where

R¹ and R² are each, independently of one another, H,—CH₃, —C₂H₅, —C₃H₇, —(CH₂) _(n)—CH₂—

-   -   x=—CH₂, CO, CS    -   y=S, NH, —(CH₂)_(m)—    -   n=0 to 9    -   m=1 to 4;        and/or compounds of the formula (II)        where    -   z=—OCH₃, —SO3H, —SO₃ ⁻M⁺, —NO₂, —NH₂, —NH—NH₂, —CO₂ ^(−M) ⁺,        —CHO,    -   M=a cation, in particular Na        and in which the molar ratio of amino resin former:        formaldehyde: sulfite: nitrogen-containing formulation auxiliary        is 1:1.9-6.0:1.0-2.0: 0.01-1.5 and/or the molar ratio of        naphthalenesulfonic acid: formaldehyde nitrogen-containing        formulation auxiliary is 1:0.7-3.0:0.01-1.5.

Contrary to all expectations, it has been found that the storage-stablesulfonated condensation products of the invention display, in additionto the desired temperature stability, a drastic reduction in theundesirable outgassing of formaldehyde and/or ammonia which has hithertobeen typical for this class of product. This effect displayed so clearlywas not foreseeable.

As regards the components of the storage-stable sulfonated condensationproducts, the invention provides for melamine and/or urea to be used aspreferred amino resin formers. These can be replaced to an extent of upto 70% by weight by thiourea, dicyandiamide, a guanidine (salt) andmixtures thereof, although ranges of from 30 to 50% by weight are to bepreferred.

Likewise, urea and also thiourea, N-methylurea, 2-imidazolidinone and/oranthranilamide represent typical organic formulation auxiliaries for thepurposes of the invention.

The nitrogen-containing formulation auxiliary can, if desired, be partlyincorporated into the condensate of amino resin former, formaldehyde andsulfite component or form an adduct with this.

For some applications, it has been found to be advantageous to use thecondensation products as aqueous solutions. Aqueous solutions having asolids content of from 20 to 60% by weight and a viscosity at 95° C. offrom 0.5 to 250 mm².s⁻¹ are particularly useful for this purpose. On theother hand, the condensation products can also be used as dry productshaving a residual moisture content of <5% (weight/weight).

Apart from the storage-stable sulfonated condensation productsthemselves, the present invention also claims a process for preparingthem, in which

-   -   a) the amino resin former or formers, formaldehyde and the        sulfite component are heated in a molar ratio of 1:1.9-6.0:        1.0-2.0 in aqueous solution with addition of a portion 1 of the        selected molar amount of the formulation auxiliary at a        temperature of from 40° C. to 90° C. and a pH of from 7.5 and        13.0 until sulfite is no longer detectable,    -   b) a portion 2 of the selected molar amount of the formulation        auxiliary is then added at a pH of from 3.0 to 7.0 and the        condensation is continued at a temperature of from 60 to 95° C.        until the condensation product has a viscosity at 95° C. of from        1 to 250 mm².s⁻¹,    -   c) the condensation product is subsequently brought to a pH of        from 7.5 to 12.0 or a thermal after-treatment is carried out at        a pH of ≧10.0 and a temperature of from 65 to 90° C. and    -   d) a portion 3 of the selected molar amount of the formulation        auxiliary is finally added,        where the sum of portion 1, portion 2 and portion 3 of the        formulation auxiliary corresponds to the molar amount of the        formulation auxiliary of the formula (I) and/or (II) and each        individual portion can amount to a proportion of from 0 to 100        total-%, with the proviso that the portion 1 is <100% and        preferably <99% and particularly preferably <90%, respectively.

Furthermore, this process provides for the condensation productsobtained in this way to be dried to a preferred residual moisturecontent of <5%, which should preferably be carried out by evaporation ofthe water under reduced pressure, in a spray drier or on a roller dryer.

As an alternative method of preparing the condensation products claimed,it is proposed that sulfonated melamine-formaldehyde condensationproducts, sulfonated melamine-urea-formaldehyde condensation products ornaphthalenesulfonic acid-formaldehyde condensation products be admixedwith from 0.1 to 50% by weight, based on the content of solid activecomponents, of a formulation auxiliary of the formulae (I) and/or (II)defined above or mixtures thereof and, if desired, dried to a residualmoisture content of <5%.

The storage-stable sulfonated condensation products are used either asadditives for inorganic binders, e.g. cement, lime, gypsum, CaSO₄hemihydrates and anhydrites, in an amount of from 0.01 to 20% by weight,based on the amount of the inorganic binders used, or else as additivefor hydraulically setting dry mixes which comprise inorganic binders, inwhich case preference is given to amounts of from 0.01 to 20% by weight,based on the amount of the inorganic binders used.

Overall, the storage-stable sulfonated condensation products of theinvention represent a significant advance in respect of the thermalstability of these condensation products and also take account of theincreased demands made of environmentally friendly products.

The following examples illustrate these advantages of the condensationproducts of the invention.

EXAMPLES Example 1 Comparison, Without Formulation Auxiliary

332.1 g of formalin (30% strength), 156.5 g of water and 0.6 g of a 20%strength aqueous sodium hydroxide solution were placed in a round-bottomflask. 126.0 g of melamine were subsequently introduced, the solutionwas heated to 30° C. and 121.3 g of sodium pyrosulfite and 16.5 g of 20%strength NaOH were added and the mixture was heated at 80° C. until thesulfite is completely incorporated.

After the sulfite had been completely incorporated, 56.0 g of H₂SO₄ (10%strength) were added and condensation was then carried out at 80° C.until the viscosity was 9.1 cSt; finally, 66.5 g of a 20% strengthsodium hydroxide solution were added and the mixture was cooled to roomtemperature (RT).

The finished solution displayed the following physical data:

-   -   Solids content: 40.7% by weight    -   Viscosity: 3.40 cSt (20° C.)    -   pH: 12.0    -   HCHO_(free): 0.40%

This solution was dried in a spray drier to give a colorless powder;HCHO_(free) content of the powder after drying: 0.22%.

Examples according to the invention: (with formulation auxiliary)

Example 2

332.1 g of formalin (30% strength), 156.5 g of water and 0.6 g of a 20%strength aqueous sodium hydroxide solution were placed in a round-bottomflask. 126.0 g of melamine were subsequently introduced, the solutionwas heated to 30° C. and 121.3 g of sodium pyrosulfite and 16.5 g of a20% strength aqueous sodium hydroxide solution were added and themixture was heated at 80° C. until the sulfite is completelyincorporated.

After the sulfite had been completely incorporated, 13.6 g ofanthranilamide and 37.0 g of N-methylurea and also 56.0 g of H₂SO₄ (10%strength) and 25.3 g of water were added and condensation was carriedout at 80° C. until the viscosity was 9.1 cSt; finally, 20.9 g of a 20%strength sodium hydroxide solution were added and the mixture was cooledto RT.

The finished solution displayed the following physical data:

-   -   Solids content: 43.8% by weight    -   Viscosity: 2.89 cSt (20° C.)    -   pH: 12.1    -   HCHO_(free): 0.27%

This solution was dried in a spray drier to give a colorless powder;HCHO_(free) content of the powder after drying: 0.19%.

Example 3

332.1 g of formalin (30% strength), 156.5 g of water and 0.6 g of a 20%strength aqueous sodium hydroxide solution were placed in a round-bottomflask. 126.0 g of melamine were subsequently introduced, the solutionwas heated to 30° C. and 121.3 g of sodium pyrosulfite and 16.5 g of a20% strength aqueous sodium hydroxide solution were added and themixture was heated at 80° C. until the sulfite is completelyincorporated.

After the sulfite had been completely incorporated, 56.0 g of H₂SO₄ (10%strength) were added and condensation was carried out at 80° C. untilthe viscosity was 9.1 cSt; 13.6 g of anthranilamide, 25.8 g of2-imidazolidinone and 20.1 g of water were then added and the solutionwas made alkaline by addition of 14.7 g of a 20% strength sodiumhydroxide solution and cooled to RT.

The finished solution displayed the following physical data:

-   -   Solids content: 43.1% by weight    -   Viscosity: 3.10 cSt (20° C.)    -   pH: 11.3    -   HCHO_(free): 0.10%

This solution was dried in a spray drier to give a colorless powder;HCHO_(free) content of the powder after drying: 0.08%.

Example 4

332.1 g of formalin (30% strength), 156.5 g of water and 0.6 g of a 20%strength aqueous sodium hydroxide solution were placed in a round-bottomflask. 126.0 g of melamine were subsequently introduced, the solutionwas heated to 30° C. and 121.3 g of sodium pyrosulfite and 16.5 g of a20% strength aqueous sodium hydroxide solution and also 37.0 g ofN-methylurea, 76.1 g of thiourea and 150.6 g of water were added and themixture was heated at 80° C. until the sulfite is completelyincorporated.

After the sulfite had been completely incorporated, 56.0 g of H₂SO₄ (10%strength) were added and condensation was carried out at 80° C. untilthe viscosity was 3.9 cSt; finally, 22.2 g of a 20% strength sodiumhydroxide solution were added and the mixture was cooled to RT.

The finished solution displayed the following physical data:

-   -   Solids content: 41.8% by weight    -   Viscosity: 2.53 cSt (20° C.)    -   pH: 12.3    -   HCHO_(free): 0.08%

This solution was dried in a spray drier to give a colorless powder;HCHO_(free) content of the powder after drying: 0.07%.

Example 5

332.1 g of formalin (30% strength), 156.5 g of water and 0.6 g of a 20%strength aqueous sodium hydroxide solution were placed in a round-bottomflask. 126.0 g of melamine were subsequently introduced, the solutionwas heated to 30° C. and 121.3 g of sodium pyrosulfite and 16.5 g of a20% strength sodium hydroxide solution and also 37.0 g of N-methylurea,19.0 g of thiourea and 92.8 g of water were added and the mixture washeated at 80° C. until the sulfite is completely incorporated.

After the sulfite had been completely incorporated, 56.0 g of H₂SO₄ (10%strength) were added and condensation was carried out at 80° C. untilthe viscosity was 5.3 cSt; finally, 15.8 g of a 20% strength sodiumhydroxide solution were added and the mixture was cooled to RT.

The finished solution displayed the following physical data:

-   -   Solids content: 40.5% by weight.    -   Viscosity: 2.84 cSt (20° C.)    -   pH: 12.0    -   HCHO_(free): 0.10%

This solution was dried in a spray drier to give a colorless powder;HCHO_(free) content of the powder after drying: 0.11%.

In the following, the properties of the resin-containing solutions andthe powders produced therefrom were compared in an α-hemihydrateenvironment:

-   -   Basic formulation: 50.0 g of α-hemihydrate        -   16.0 g of water        -   0.180 g of the respective amino resin (calculated as solid)            Procedure:

The fluidized plaster slurries were poured from the mixing cup onto aglass plate in one action; after determining the spread (SP), settingwas monitored by means of a Vicat needle about 1 cm from the edge of thegypsum plaster cake.

Results: as solution as powder Δt of SP Setting SP Setting settingExamples [cm] [min] [cm] [min] [min] 1 (comparison) 10.2 35 10.6 43 8 28.8 33 8.7 35 2 3 9.9 41 9.3 41 0 4 9.5 35 9.6 33 −2 5 9.8 35 9.9 33 −2

It can be seen that, in examples 2 to 4 according to the invention,setting of the gypsum plaster mix remains unchanged within the limits ofaccuracy when the solution has been spray dried to give a powder, whileexample 1 (comparison) without addition according to the invention of aformulation auxiliary displays a significantly prolonged setting time.

The same significant result can be seen in the change in the HCOH_(free)values after drying (cf. examples 1 to 5). In example 1 (comparison)there is a relatively large decrease in the concentration of unreactedformaldehyde, while the resins of examples 2 to 4 according to theinvention display excellent thermal stability during drying.

1. A storage-stable sulfonated condensation product based on an aminoresin former having at least two amino groups, at least one of sulfiteand naphthalenesulfonic acid; and formaldehyde and, optionally organicnitrogen bases, comprising: at least one nitrogen-containing formulationauxiliary selected from the group consisting of a compound of formula(1)R₁—NH—X—Y—R²  (1) wherein R¹ and R² are independently H, —CH₃, —C₂H₅,—C₃H₇ or together form —CH₂)_(n)—CH₂—; X is —CH₂, CO, or CS; Y is S, NH,or —(CH₂)_(m); — n is 0 to 9 m is 1 to 4; and a compounds of formula(II)

whereinZ is —OCH₃, —SO₃H, —SO₃ ⁻M⁺, —NO₂, —NH₂, —NH—NH₂, —CO₂ ⁻M⁺, —CHO, or H Mis a cation; wherein the molar ratio of amino resin former:formaldehyde: sulfite: nitrogen-containing formulation auxiliary is1:1.9-6.0:1.0-2.0:0.01-1.5 and/or the molar ratio ofnaphthalene-sulfonic acid: formaldehyde: nitrogen-containing formulationauxiliary is 1:0.7-3.0:0.01-1.5.
 2. A condensation product as claimed inclaim 1, wherein said amino resin former is selected from the groupconsisting of melamine and urea.
 3. A condensation product as claimed inclaim 1, wherein said formulation auxiliary is selected from the groupconsisting of urea, thiourea, N-methylurea, 2-imidazolidinone andanthranilamide as formulation auxiliaries.
 4. A condensation product asclaimed in claim 1, wherein the amino resin former comprises up to 70%by weight of at least one of thiourea, dicyandiamide, a guanidine, and aguanidine salt.
 5. A condensation product as claimed in claim 1, whereinthe condensation product is an aqueous solution having a solids contentof from 20 to 60% by weight.
 6. A condensation product as claimed inclaim 5, wherein the viscosity of the aqueous solution at 95° C. is from0.5 to 250 mm².s⁻¹.
 7. A condensation product as claimed in claim 1,wherein the aqueous solution has been dried to a residual moisturecontent of <5%.
 8. A process for preparing a condensation product asclaimed in claim 1, comprising: a) heating said amino resin former orformers, said formaldehyde and said sulfite component in a molar ratioof 1:1.9-6.0:1.0-2.0 in aqueous solution with addition of a portion ofthe selected molar amount of the formulation auxiliary at a temperatureof from 40° C. to 90° C. and a pH of from 7.5 and 13.0 until sulfite isno longer detectable; b) adding a portion 2 of the selected molar amountof the formulation auxiliary at a pH of from 3.0 to 7.0 and continuingthe condensation at a temperature of from 60 to 95° C. until thecondensation product has a viscosity at 95° C. of from 1 to 250 mm².s⁻¹;c) adding the pH of condensation product to a pH of from 7.5 to 12.0 orconducting a thermal after-treatment at a pH of ≧10.0 and a temperatureof from 65 to 90° C.; and d) adding a portion 3 of the selected molaramount of the formulation auxiliary; wherein the sum of portion 1,portion 2 and portion 3 of the formulation auxiliary corresponds to themolar amount of the formulation auxiliary of the formula (I) and/ (II)and each individual portion can amount to a proportion of from 0 to 100total-%, wherein portion 1 is <100%.
 9. The process as claimed in claim8, wherein the resultant condensation products are dried in a spraydrier or on a roller drier to a preferred residual moisture content of<5% by evaporation of the water under reduced pressure.
 10. A processfor preparing a condensation product as claimed in claim 1, wherein thesulfonated melamine-formaldehyde condensation products, sulfonatedmelamine-urea-formaldehyde condensation products or naphthalenesulfonicacid-formaldehyde condensation products are admixed with from 0.1 to 50%by weight, based on the content of solid active components, of aformulation auxiliary of the formula (I) and (II) or mixtures thereofand dried to a residual moisture content of <5%.
 11. An inorganicbinders comprising from 0.01 to 20% by weight of condensation product asclaimed in claim 1, based on the amount of the inorganic binders.
 12. Anhydraulically setting dry mixes comprising from 0.01 to 20% by weight,of a condensation product as claim in claim 1, based on the amount ofinorganic binders.